OVERVIEW

What is malignant otitis externa?

Malignant otitis externa, also known as necrotizing otitis externa or skull base osteomyelitis, is an aggressive infection caused primarily by Pseudomonas aeruginosa bacteria invading the ear canal, with subsequent spread to the adjacent temporal bone marrow and brain tissues.

It causes persistent severe ear pain, particularly noticeable at night, along with ear discharge, fever, significant headache, and may even lead to neurological symptoms such as facial paralysis.

Malignant otitis externa is neither contagious nor hereditary, but without prompt treatment, it can lead to life-threatening complications such as meningitis, brain abscess, or even encephalomalacia.

Is malignant otitis externa common?

No, it is rare.

SYMPTOMS

What are the common manifestations of malignant otitis externa?

• The most typical symptom is severe ear pain, which may also occur when touching the tragus. The pain is more noticeable at night and may be accompanied by chewing pain, headache, etc. Additionally, patients may experience discharge from the external ear canal.

• Significant systemic discomfort and fever may also occur.

• A few cases may present with neurological paralysis symptoms, such as cranial nerve palsy or facial nerve palsy (facial paralysis).

What complications or serious consequences can malignant otitis externa cause?

If the infection of malignant otitis externa progresses and spreads to the base of the brain, it may lead to skull base osteomyelitis, temporomandibular joint osteomyelitis, life-threatening cranial nerve palsy, as well as meningitis, brain abscess, encephalomalacia, dural venous sinus thrombosis, or even death.

CAUSES

What are the common triggers of malignant otitis externa?

Malignant otitis externa commonly occurs in elderly diabetic patients, immunocompromised individuals such as children with malignancies or malnutrition, and HIV-infected individuals. These susceptible groups are more likely to develop malignant otitis externa under the following circumstances:

• Water entering the ear canal, such as during swimming.
• Skin damage in the ear canal.
• Long-term use of hearing aids or earphones.

In the above situations, infection with Pseudomonas aeruginosa (in over 95% of cases) is the primary cause, while in rare instances, other infections such as Aspergillus may lead to malignant otitis externa.

Who is most commonly affected by malignant otitis externa?

Malignant otitis externa is most commonly seen in elderly diabetic patients, children with malignancies or malnutrition, and HIV-infected individuals.

Is malignant otitis externa contagious?

No, it is not contagious.

Is malignant otitis externa hereditary?

No, it is not hereditary.

DIAGNOSIS

How is malignant otitis externa diagnosed?

• Typical symptoms: Severe ear pain, pain when touching the tragus, noticeable nighttime pain, pain while chewing, headache, discharge from the external auditory canal, and possible systemic discomfort, fever, etc. Neurological paralysis symptoms may also occur.

• High-risk groups: This disease commonly affects elderly diabetic patients, children with malignancies or malnutrition, or HIV-infected individuals.

• Recent exposure to water in the external auditory canal (e.g., swimming), recent skin damage in the external auditory canal, or prolonged use of hearing aids or earphones.

• Physical examination: The doctor may observe redness in the auricle and tragus. Severe pain may occur when pressing the tragus or pulling the auricle.

• Otoscopy: Reveals granulation tissue at the osteocartilaginous junction of the external auditory canal, redness and swelling of the external auditory canal, and various necrotic secretions.

• Culture of external auditory canal discharge: May detect Pseudomonas aeruginosa infection.

What tests are needed to diagnose malignant otitis externa?

• Blood tests: Significant elevation in erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP).

• Otoscopy: Shows granulation tissue at the osteocartilaginous junction of the external auditory canal, redness and swelling, and necrotic secretions.

• Culture of external auditory canal discharge: A small swab is used to collect secretions for testing, primarily to identify Pseudomonas aeruginosa infection, and occasionally other microorganisms like Aspergillus.

• Blood culture: Performed if systemic fever is present.

• Ear MRI or CT scan: Reveals abnormal signs of infection spreading to bony structures or intracranial areas.

• Bone scan: A positive result can aid in diagnosis.

• Pathological examination: Helps differentiate malignant otitis externa from temporal bone squamous cell carcinoma.

What diseases can malignant otitis externa be easily confused with?

• Simple otitis externa: Ear pain is relatively milder, microbial culture of discharge differs, and ear MRI or CT can assist in diagnosis.

• External auditory canal cancer: Symptoms include ear pain and bloody discharge. Abnormal growth in the external auditory canal or failure of long-term otitis externa treatment should raise suspicion. Common symptoms are mild pain and bloody discharge. Pathological examination can confirm the diagnosis.

TREATMENT

Which department should I visit for malignant otitis externa?

Otolaryngology (ENT) department.

What are the treatment options for malignant otitis externa?

• For infections caused by Pseudomonas aeruginosa: Systemic anti-pseudomonal antibiotics (e.g., fluoroquinolones) are used. If resistant, drugs like piperacillin may be prescribed. Treatment typically lasts 6 weeks with 4 courses.

• For Aspergillus infections: Antifungal therapy (e.g., voriconazole or amphotericin) is administered.

• Symptomatic relief with sedatives or painkillers may be provided.

• Debridement of the ear canal: Rarely performed.

• Refractory cases may occasionally undergo hyperbaric oxygen therapy, though efficacy is uncertain.

What are the common side effects of medications for malignant otitis externa?

• Fluoroquinolones: May cause tendinitis, tendon rupture, or joint/tissue damage.

• Piperacillin: May cause gastrointestinal side effects like nausea or vomiting.

Is follow-up necessary for malignant otitis externa? How is it done?

Yes. Initial follow-ups may occur every 2–3 days, with intervals gradually extended as determined by the treating physician.

Can malignant otitis externa be completely cured?

Yes, timely treatment can lead to a full recovery.

Can malignant otitis externa recur after treatment? What to do if it recurs?

Recurrence is possible. If symptoms return, seek immediate medical attention for diagnosis and standardized treatment.

DIET & LIFESTYLE

What should patients with malignant otitis externa pay attention to in their diet?

There are no special dietary restrictions. A healthy diet is sufficient.

What should patients with malignant otitis externa pay attention to in daily life?

• During recovery, avoid getting water in the ear. When showering, placing a cotton ball coated with petroleum jelly in the ear canal can prevent water entry.

• Avoid swimming during malignant otitis externa.

• Do not wear hearing aids or headphones during malignant otitis externa.

PREVENTION

Can Malignant Otitis Externa Be Prevented? How to Prevent It?

Malignant otitis externa can be prevented. Elderly diabetic patients, children with malignancies or malnutrition, or HIV-infected individuals should pay special attention to the following:

• Avoid using hard objects to clean the ears, such as fingers, towels, cotton swabs, or other rigid items.

• After water enters the ear canal, promptly shake it out or use a hairdryer to dry the ears.

• Avoid prolonged use of hearing aids or earphones. Hearing aids should be removed at night and cleaned regularly.

• Actively manage blood sugar levels.

• Keep the ear canal clean.

• Prevent shampoo, conditioner, or similar products from entering the ear canal.